Monte Carlo lattice simulation of the interchange of chains between micelles of diblock copolymers

Abstract

The exchange of chains between micelles of diblock copolymers in dilute solution has been studied using a dynamic Monte Carlo simulation. Appropriate correlation functions have been defined and used to extract information from the trajectories. The picture of the dynamics depends on the definition of the correlation functions, because different definitions are sensitive to different aspects of the overall dynamics of the system. The influence of concentration on the fundamental processes, such as the extraction of a chain from a micelle and the addition of a chain to a micelle, is studied. The tracer correlation function, wich is defined in terms of the number of chains in an aggregate, shows a concentration dependence. In contrast, correlation functions defined for the extraction of a chain from a micelle and addition of a chain to a micelle change very little for concentrations slightly above the critical micelle concentration. An elaborated form of the correlation function for chain addition to a micelle, which differentiates the arriving chain as a free chain or a participant in an aggregate at t = 0, shows a concentration dependence for the latter case. Another formulation on the basis of fluorescence experiments has been set up considering each chain to be labelled either with a Förster donor or a Förster acceptor. The resulting curves show that an increase in concentration leads to the relatively faster change in the efficiency of nonradiative singlet energy transfer.